Ext.ux.TreeCheckNodeUI = function(){
    //多选: 'multiple'(默认)
    //单选: 'single'
    //级联多选: 'cascade'(同时选父和子);'parentCascade'(选父);'childCascade'(选子)
    this.checkModel = 'multiple';
    //only leaf can checked
    this.onlyLeafCheckable = false;
    Ext.ux.TreeCheckNodeUI.superclass.constructor.apply(this, arguments);
};

Ext.extend(Ext.ux.TreeCheckNodeUI, Ext.tree.TreeNodeUI, {
    renderElements: function(n, a, targetNode, bulkRender){
        var tree = n.getOwnerTree();
        this.checkModel = tree.checkModel || this.checkModel;
        this.onlyLeafCheckable = tree.onlyLeafCheckable || false;
        // add some indent caching, this helps performance when rendering a large tree
        this.indentMarkup = n.parentNode ? n.parentNode.ui.getChildIndent() : '';
        //var cb = typeof a.checked == 'boolean';
        var cb = (!this.onlyLeafCheckable || a.leaf);
        var href = a.href ? a.href : Ext.isGecko ? "" : "#";
        var buf = ['<li class="x-tree-node"><div ext:tree-node-id="', n.id, '" class="x-tree-node-el x-tree-node-leaf x-unselectable ', a.cls, '" unselectable="on">', '<span class="x-tree-node-indent">', this.indentMarkup, "</span>", '<img src="', this.emptyIcon, '" class="x-tree-ec-icon x-tree-elbow" />', '<img src="', a.icon || this.emptyIcon, '" class="x-tree-node-icon', (a.icon ? " x-tree-node-inline-icon" : ""), (a.iconCls ? " " + a.iconCls : ""), '" unselectable="on" />', cb ? ('<input class="x-tree-node-cb" type="checkbox" ' + (a.checked ? 'checked="checked" />' : '/>')) : '', '<a hidefocus="on" class="x-tree-node-anchor" href="', href, '" tabIndex="1" ', a.hrefTarget ? ' target="' + a.hrefTarget + '"' : "", '><span unselectable="on">', n.text, "</span></a></div>", '<ul class="x-tree-node-ct" style="display:none;"></ul>', "</li>"].join('');
        var nel;
        if (bulkRender !== true && n.nextSibling && (nel = n.nextSibling.ui.getEl())) {
            this.wrap = Ext.DomHelper.insertHtml("beforeBegin", nel, buf);
        }
        else {
            this.wrap = Ext.DomHelper.insertHtml("beforeEnd", targetNode, buf);
        }
        this.elNode = this.wrap.childNodes[0];
        this.ctNode = this.wrap.childNodes[1];
        var cs = this.elNode.childNodes;
        this.indentNode = cs[0];
        this.ecNode = cs[1];
        this.iconNode = cs[2];
        var index = 3;
        if (cb) {
            this.checkbox = cs[3];
            Ext.fly(this.checkbox).on('click', this.check.createDelegate(this, [null]));
            index++;
        }
        this.anchor = cs[index];
        this.textNode = cs[index].firstChild;
    },
    // private
    check: function(checked){
        var n = this.node;
        var tree = n.getOwnerTree();
        this.checkModel = tree.checkModel || this.checkModel;
        if (checked === null) {
            checked = this.checkbox.checked;
        }
        else {
            this.checkbox.checked = checked;
        }
        n.attributes.checked = checked;
        tree.fireEvent('check', n, checked);
        if (this.checkModel == 'single') {
            var checkedNodes = tree.getChecked();
            for (var i = 0; i < checkedNodes.length; i++) {
                var node = checkedNodes[i];
                if (node.id != n.id) {
                    node.getUI().checkbox.checked = false;
                    node.attributes.checked = false;
                    tree.fireEvent('check', node, false);
                }
            }
        }
        else 
            if (!this.onlyLeafCheckable) {
                if (this.checkModel == 'cascade' || this.checkModel == 'parentCascade') {
                    var parentNode = n.parentNode;
                    if (parentNode !== null) {
                        this.parentCheck(parentNode, checked);
                    }
                }
                if (this.checkModel == 'cascade' || this.checkModel == 'childCascade') {
                    if (!n.expanded && !n.childrenRendered) {
                        n.expand(false, false, this.childCheck);
                    }
                    else {
                        this.childCheck(n);
                    }
                }
            }
    },
    // private
    childCheck: function(node){
        var a = node.attributes;
        if (!a.leaf) {
            var cs = node.childNodes;
            var csui;
            for (var i = 0; i < cs.length; i++) {
                csui = cs[i].getUI();
                if (csui.checkbox.checked ^ a.checked) {
                    csui.check(a.checked);
                }
            }
        }
    },
    // private
    parentCheck: function(node, checked){
        var checkbox = node.getUI().checkbox;
        if (typeof checkbox == 'undefined') {
            return;
        }
        if (!(checked ^ checkbox.checked)) {
            return;
        }
        if (!checked && this.childHasChecked(node)) {
            return;
        }
        checkbox.checked = checked;
        node.attributes.checked = checked;
        node.getOwnerTree().fireEvent('check', node, checked);
        var parentNode = node.parentNode;
        if (parentNode !== null) {
            this.parentCheck(parentNode, checked);
        }
    },
    
    // private
    childHasChecked: function(node){
        var childNodes = node.childNodes;
        if (childNodes || childNodes.length > 0) {
            for (var i = 0; i < childNodes.length; i++) {
                if (childNodes[i].getUI().checkbox.checked) {
                    return true;
                }
            }
        }
        return false;
    },
    toggleCheck: function(value){
        var cb = this.checkbox;
        if (cb) {
            var checked = (value === undefined ? !cb.checked : value);
            this.check(checked);
        }
    }
});
